Automatic oscillation starter



Jan. 10, 1939. w. EfKocK ET AL AUTOMATIC OSCILLATION STARTER Filed May '7, 1936 7 NE in.

k ma) KW lA/VfA/TOEJ K M 6 Wm M 5 P 7 mm ATTUE/Vf) Patented Jan. 10, 1939 UNITED STATES H 2,143,822 AUTOMATIC OSCILLATION STARTER Winston E. Keck and John F. Jordan, Cincinnati, Ohio, assignors to The Baldwin Company,

Cincinnati, Ohio Application May 7, 1936, Serial No. 78,441

7 Claims.

raise the plate voltage from zero to rated value.

The object of our invention is a means of gradually raising the voltage applied to the plate of a gaseous discharge oscillator from zero to rated value, through the use of a three element vacuum tube, the cathode of which has a longer heating time than the cathode of the gaseous discharge oscillator in order to produce an initial delay. And further, a means of introducing an additional delay to take care of sudden inter- :ruptions of the voltage while the cathode of the three element vacuum tube is still hot.

Feeding the current for the gaseous oscillator thru a three element vacuum tube with relatively slow heating cathode enables the voltage inthe gas "triode to be brought up gradually since the initial resistance of the vacuum tube is high because its cathode is still relatively cold.

However, another delay must be introduced to take care of sudden interruptions and reapplication of the voltage since the cathode of the gas triode will now be hot. This is done by putting a suitable time delay in the grid of the vacuum tube by means of suitable condensers and resistances as will be fully designated.

The drawing shows the circuit with one generator although it is understood other generators will follow.

In the drawing, we show a source of current such as an AC line, and a switch S2, for connecting this current to the primary of a power transformer T. There are two secondary windings F and F. to supply filament voltage to a vacuum,

tube A and a gaseous discharge tube B. Another secondard, F3, supplies AC to a rectifier and filter circuit, so marked. Leads 8 and 9, positive and negative leads respectively, from the filter, supply current to resistor R5, and to tube B thru tube A. Part of the voltage drop across R is used for negative bias for tube B as shown. The circuit including R2, R1, R, C1 and L are associated with -tube B as a grid-coupled gaseous discharge osciland B immediately begin to heat. The cathode of tube A heats at a slower rate than that of tube B, such that when tube B is operative the resistance of tube A is large and the voltage applied to plate of tube B is very low. As the cathode of tube A heats up, the resistance of said tube decreases gradually raising the voltage on tube B.

Should switch S; be opened and immediately closed again, the cathode of tube A will still be hot. However, the potential of the grid of tube A would tend to be negative with respect to the cathode by reason of condenser C2 connected to lead 9, and the initial resistance of tube A would again be high. Condenser 0, would then gradually charge through resistance R4 and the grid of tube A would slowly become positive with respect to cathode, decreasing the resistance of tube A and gradually raising the voltage on tube B as required.

Having thus explained our invention, what we claim and wish to protect by Letters Patent is:

1. In combination, an inductive glow discharge oscilator comprising a glow discharge tube and a tuned control circuit therefor, whereby the frequency of said oscillator is stabilized, a source of current for said oscillator and means for applying the voltage of said current source gradually across said glow discharge tube, said means comprising a thermionic tube as series resistance means located between said oscillator and said source of current.

2. In combination, an inductive glow discharge oscillator comprising a glow discharge tube and a tuned control circuit therefor, whereby the frequency of said oscillator is stabilized, a source of current for said oscillator and means for applying the voltage of said current source gradually across said glow discharge tube, said means comprising a thermionic tube as series resistance means located between said oscillator and said source of current, said inductive glow discharge tube and said thermionic tube each having indirectly heated cathodes, the heat time cycle for the cathode of the thermionic tube being at least as long as the cycle for the glow discharge tube.

3. In combination, an inductive glow discharge oscillator comprising a glow discharge tube and a tuned control circuit therefor, whereby the frequency of said oscillator is stabilized, a source of current for said oscillator and means for applying the voltage of said current source gradually across said glow discharge tube, said means comprising a thermionic tube as series resistance means located between said oscillator and said tube and a three element glow discharge tube, a supply circuit for said tube comprising a source of plate potential, said thermionic tube being in series in said supply circuit with said glow'discharge tube, whereby the plate resistance of said thermionic tube controls the-potentialimpressed across said glow discharge tube, a common potential supply circuit for the grids of said tubes, a capacity in series in said circuit with the grid of said thermionic tube and a resistance connecting a said grid with the plate of said tube, whereby upon initial closing of said supply'circuit, the grids of bothof said tubes assume anegative bias and whereby through the action of said condenser and said resistance, the grid of said thermionic tube ultimately but gradually assumes a positive bias so as to impress the voltage in said supply circuit gradually across said glow discharge tube.

5. In combination, a three element thermionic tube and a three element glow discharge tube, a supply circuit for said tube comprising a source of plate potential, said thermionic tube being in seri'es'in'said supply circuit with said glow discharge tube,.whereby the plate resistance of said thermionic tube controls the'potential impressed across said glow discharge tube, a common potential supply circuit for the grids of said tubes, a capacity in series in said circuit with the grid of said thermionic tube and a resistance connecting said grid with the'plate of said tube, whereby upon initial closing ofv said supply circuit, the grids of both of said tubes assume a negative bias and whereby through the action of said condenser and said resistance, the grid of said thermionic tube ultimately but gradually assumes a positive bias so as to impress the voltage in said supply circuit gradually across said glow discharge tube, each of said tubes having an indirectly heated cathode, the time cycle of heating of the cathode of said thermionic tube being at least as long as the time cycle of heating of the cathode of said glow discharge tube. 6. In a device for the purpose described a glow discharge oscillator comprising a glow discharge tube, a tuned stabilizing circuit therefor, and a supply circuit therefor, containing a source of potential, a thermionic tube in series with said glow discharge tube in said supply circuit, said thermionic tube being of the three element type, and automatically acting means effective upon the energization of said supply circuit to change the grid potential of said thermionic tube from a negative to a positive value gradually, whereby to impress gradually across said glow discharge tube the potential of said supply circuit.

fl. In combination for the purpose described an inductive glow discharge oscillator of the three element type, a supply circuit therefor, and a thermionic tube in series therewith in said supply circuit, and means for bringing the grid of said glow discharge tube to operating potential prior to the application of the full voltage in said supply circuit across said glow discharge tube, said means comprising a connection between the grids of said tube efiective initially to bias the grid of said thermionic tube negatively, and capacitative and resistance means in the circuit of the grid of said thermionic tube efiectivegradually to change the bias thereof to a positive value.

WINSTON E. KOCK. JOHN F. JORDAN. 

